fireball: Use by-name partitions in fstab

* Also change encryption to use the 'extra' partition.
* Also remove recovery specific fstab

Change-Id: I947530ea5d3c80fb7e483a4866fc0fad3cc54ac6
fireball: default to MTP USB mode

You can't default to ADB since user is required to enable USB debugging
before adb kicks in. UMS was deprecated to help save users from
themselves (unclean unmounts and apps left wondering what happened to
their storage volume). We should at least default to MTP, even if users
will opt to change this later.

Change-Id: I90efa1aa8f8c040fe616131cba6939d0a2f4cf57
fireball: Create firmware symlinks at build time

Change-Id: I16e16943fb130d684ac425c1d4aedcdfd044e089